Suppose the charge on the capacitor at time t is Q.
The electric field between the plates of the capacitor is,
E=Qε0A
The flux through the area considered is,
ϕE=E×A2=Qε0A×A2=Q2ε0
The displacement current is given by
Id=ε0dϕEdt
Id=ε0(12ε0)dQdt
⇒Id=i2
Hence, option (B) is correct.